I'm still waiting on my DPMS 24" in .308, so I'm doing a lot of reading.  New barrel breakin obviously helps smooth any roughness in the barrel.  Handlapping smoothes and polishes the barrel to increase accuracy.  Now I'm reading about abrasive bullets by David Tubbs.  Nothing I've read is negative.  Supposedly you can use the abrasive bullets to breakin, smooth and polish a new barrel, increasing muzzle velocity, accuracy, and decreasing fouling.
Does anyone have experience with Tubb's system?  Should I have the barrel lapped before of after breakin?  Suggested breakin procedure and type of rounds to use for breakin?  Do moly coated rounds really make a difference in breakin?
Thanks

This is a good question that gets lots of discussion...  There are various folks who believe completely different things about barrel break-in.  I know I've seen a write-up by Gale McMillan who said that barrel break-in was a way for barrel makers to sell more barrels.  But, then you have David Tubbs and he is selling these abrasive bullets and that guy has an impressive record...  So, I think we are back where we started...

Spooky

It all depends on your barrel and what your going to do with it.

If your going to just shoot it. No lapping required. However if you have one of those "match" barrels you may want to do that.

I think the rule of thumb is..
Chrome Barrel - not required
Non-Chrome Barrel - may be required depending on your planned use.


I "broke" my chrome and non-chrome barrels in by just shooting them. For me, that is all I need.

A hand lapped barrel would be made worse by that system and "unpolish" the barrel.  It only helps to do a ghetto fire lapping to non lapped factory barrels which are rough.  Just shooting any gun will improve its accuracy whether lapped or not for the first few hundred rounds.  You dont need to clean every certain number of rounds etc.  Hope that helps.